Source : Webster's Revised Unabridged Dictionary (1913)

Carboxide \Car*box"ide\, n. [Carbon + oxide.] (Chem.)
   A compound of carbon and oxygen, as carbonyl, with some
   element or radical; as, potassium carboxide.

   {Potassium carboxide}, a grayish explosive crystalline
      compound, {C6O6K}, obtained by passing carbon monoxide
      over heated potassium.